Background: Low back pain (LBP) is a disability-leading condition globally, with increased burden in rural settings caused by lifestyle and health disparities. Vitamin D3 deficiency has been put forth as a modifiable risk factor for musculoskeletal pain, but its potential in rural communities is underexposed. Objectives: To assess the rate of deficiency of vitamin D3 among patients with low back pain from rural populations and to determine its correlation with the severity of pain. Methods: A prospective observational study was conducted on 500 patients presenting with low back pain of two weeks or more duration and without neurological impairment. Serum vitamin D3 levels were estimated at presentation and categorized as deficient (<20 ng/mL), insufficient (20–29 ng/mL), or sufficient (≥30 ng/mL). Pain intensity was assessed using Visual Analog Scale (VAS) scores, and the relationship between vitamin D3 status and pain severity was evaluated. Result: Among the study participants, 65.0% were vitamin D3 deficient, 23.0% were insufficient, and only 12.0% had sufficient vitamin D3 levels. The mean VAS score was highest in the deficient group (7.3 ± 1.1), followed by the insufficient group (6.0 ± 1.2), and lowest in the sufficient group (4.8 ± 1.3). Statistical analysis revealed that lower vitamin D3 levels were significantly associated with higher pain severity (p < 0.001). Conclusion: vitamin D3 deficiency is linked to increased pain intensity and is very common among patients with low backaches in rural areas. In rural areas with limited resources, routine vitamin D3 screening and correction may be an affordable way to lessen the burden of LBP.